Thats an interesting one.......Take the front flexi bit off then smash the internals out of the cat.......Is it easy to get the flexi off as my mechanical skills are not the best.....Although I did take the EGR and inlet manifold off yesterday and gave them a good clean, was well happy with myself!! So a de-cat on a TDCI will release lots more horses.....Excellent! What about this thing on Google I read about the Turbo needing the Cat for back pressure or was that bloke talking out his a$$?